Multiple Fact Tables Slice one table with second table categories

I looked around A LOT but could not find the answer, I'd appreciate some help here!

I have a data model with 2 fact tables: [A] Product Sales & [B] Expenses Per Product Per Channel.

I need to report based on the Sales [A] so my goal is to be able to bring the total expenses per product from [B] into the sales table [A] and in case a drill down is needed, to be able to slice that total into the different channels. In other words: Import total value from B into A, then slice value with B categories.

NOTES:

1. I tried, but I cannot append both tables into one big flat table as each has about 30 million rows.
2. The categories in table B (sales channel) vary over time so I decided to unpivot and keep just one column "Channel"
3. All other dimension tables are in place to describe Product, Channel and Dates.
4. I could add a detailed visualisation and share the dimensional filters however I'd like to have all into one single view.

Here some simplified snapshots of what I have and what I'd expect (and Excel sample attached)

Fact Tables A & B

Expected Pivot/Visualization

Here the Excel file: https://docs.google.com/spreadsheets/d/1UBv4zmDH4AAylcLiFeEXqTF0D9QNhJB4/edit?usp=sharing&ouid=116638270489810037812&rtpof=true&sd=true